I have always struggled with what to take and what too leave at home.
I always take one full complete set of kit. I use a Poseidon Besea W50 BCD which takes up the most room and is reasonably heavy, but it is just so comfortable and are made to perfection. They are more or less built to your frame and it has a hard back plate which takes a lot of weight off your spine when your not in the water. I have done 300 or so dives with this BCD and it still looks like new, a little wear and tear but nothing much.
Always use my own regs, I have changed the hoses to mi-flex hoses which will reduce the weight down to a bare minimum and are well worth adding to your regs if you come across them. One set of Scubapro twin jet max fins, again heavyish, and a couple of spare spring straps, I take two Atomic masks and a snorkel, a 3mm full length wetsuit and boots. I always take an SMB, a few tools, just a screwdriver and an adjustable spanner and a decent torch. Problem regarding the torch is that the body is heavy, and so are the interchangeable heads for it, (you can use either an HID/ LED or a standard bulb fitting, but they come as three seperate heads) so I just take the HID head which is the brightest and has a longer burn time, but on the downside, is also the heaviest.
That all goes in as check in luggage......I hate it, it's just such a gamble and it never sits easy with me. I try if possible to squeeze my torch in my carry on bag as that cost me $1200 and would be a pain in the ass to lose. My regs I always try to carry on too but it's not always possible.
I take my computer, 2 x cameras, 2 x underwater housings, my wide angle lense (which cost me ridiculous money even after importing it direct from Japan at half the cost it would of done if I bought it from the UK, so that definately stays with me) and a macro lense, spare parts for the cameras, and my log book all goes into my carry-on. I don't really log my dives any more so I just have my diving cards and I keep maps and information etc in my log book these days. My carry-on is rammed, and it's heavy so it's always a massive struggle to then get in a torch and regs. I always end up having to make a decision of what to take with me and what goes in the hold. We have these metal frame things in London which you are asked to place your carry-on bag inside it to make sure its the correct size, if it dosent fit inside you can't take the carry-on on to the plane, so you can't really scam more things on like you could a few years ago.
I normally then pack in the minimum clothes, you can't afford to dress to impress and that's it...I just hate packing ! If diving from a resort, I would do the same as you Eric, regs, computer, mask, fins, SMB, and camera stuff and then rent the rest. If you know the rental gear is ok, make the most of it mate as it will save you dragging tons of gear around.